Final answer:
The average leeway space in the mandible, traditionally considered to be 5 millimeters side-to-side and 7-8 millimeters deep, might actually require up to 8 tooth diameters side-to-side and 15 diameters deep according to newer research.
Step-by-step explanation:
The average leeway space on each side of the mandible refers to the difference in size between the primary second molars and the permanent premolars that will replace them. Traditionally, the rule of thumb for leeway space was 5 millimeters side-to-side and 7-8 millimeters deep. However, more recent studies indicate that the required leeway space might be substantially larger, suggesting up to 8 tooth diameters side-to-side and 15 diameters deep to adequately accommodate future dental changes.